50 ARISAEMA TRIPHYLLUM 
without taking a peripheral position initiate the endosperm forma- 
tion by producing cross walls in various planes. Later endosperm 
growth is brought about primarily through the activity of a defi- 
nite meristematic region. 
The second daughter of the primary endosperm nucleus does 
not divide but organizes the residual cavity of the embryo-sac 
into a large nutritive cell which elaborates food material for the 
growing endosperm. 
Pollination is secured by insect visitation. An unknown 
attraction for insects is evident in the pistillate inflorescence. 
Primary roots of seedlings are diarch in structure. Secondary 
roots of seedlings and all roots of mature plants show a three- to 
five-radiate structure. 
A small percentage of seedlings regularly do not produce func- 
tional plumules the first season. 
The sex of mature plants is changeable, and the amount of 
water available at a certain period in development is directly or 
indirectly responsible for such change. 
Abnormal flowers showing a tendency toward bisexual structure 
have been found. 
The corms may harbor perennial mycelium of Uromyces caladit. 
The writer wishes to express his deep appreciation of the kind 
interest and helpful suggestions of Professor D. M. Mottier of 
Indiana University, under whose direction the present work has 
been done. 
